1. Field of the Invention
The invention relates to a cell line obtained from Heliothis subflexa, designated BCIRL-HS-AM1, and a process of producing viral agents such as viruses, viral particles, and/or inclusion bodies in vitro. The cell line finds particular utility in the production of baculoviruses, and especially occlusion bodies (OB) of the baculoviruses Anagrapha (Syngrapha) falcifera multiple nuclear polyhedrosis virus (AfMNPV) and Autograph californica multiple nuclear polyhedrosis virus (AcMNPV).
2. Description of the Prior Art
Baculoviruses are valuable as biological control agents for Lepidopteran pests. The viruses are currently mass-produced in vivo in insect larvae under nonaseptic conditions. The process is difficult to control and the viruses thus produced are subject to contamination. Further, the process is labor-intensive requiring the continuous supply of insect larvae in which the viruses are produced.
Autographa californica multiple nuclear polyhedrosis virus is well recognized for its use as a potential biocontrol agent because of its wide host range within the order Lepidoptera. Anagrapha falcifera multiple nuclear polyhedrosis virus is a baculovirus recently isolated from a celery looper and differs from AcMNPV both in its REN pattern and its greater infectivity for Helicoverpa zea larvae. AfMNPV is equally infectious for both H. zea and H. virescens larvae and possesses a wide range infecting over 30 species from 10 families in the order Lepidoptera.
Insect cell lines have been established from major Lepidopteran pests of agriculture and forestry [Hink et al., Invertebrate Cell Culture Media and Cell Lines In "Techniques in Setting Up and Maintenance of Tissue and Cell Cultures", E. Kurstak, ed., Elsevier, N.Y. pp. 1-30 (1985)]. These cell lines and techniques have been identified as the future source of mass-produced viral insecticides. Before cell technology can be a viable alternative to in vivo production of insecticides, however, the conditions for in vitro production must be systematically evaluated and optimized [McIntosh et al., J. Kansas Entomol. Soc. 55: 354-386 (1982)].